US20210362078A1 - Self-cleaning screen - Google Patents

Abstract

Various implementations include a self-cleaning screen device including a screen and auger. The screen is a hollow cylinder and has a screen central axis, a screen inner surface, a screen outer surface opposite and radially spaced apart from the screen inner surface, a screen first end, and a screen second end opposite and axially spaced apart from the screen first end. The screen outer surface defines a plurality of openings extending radially to the screen inner surface. The auger is helically shaped and has an auger central axis, an auger first end, and an auger second end opposite and axially spaced apart from the auger first end. The auger is disposed around at least a portion of the screen outer surface such that the auger central axis and the screen central axis are coincident with each other. The auger is rotatable about the auger central axis relative to the screen.

Description

BACKGROUND
• Pit latrines are typically holes formed in the ground for the intended use of collecting human urine and feces. Pit latrines are often used in developing countries where waste management is unavailable. As a pit latrine fills, the pit latrine must be emptied.
• Some methods for emptying pit latrines include suctioning the contents of the pit latrine. However, larger items such as garbage, rocks, and plant matter sometimes accumulate in pit latrines. These larger items can clog or bind the driving mechanisms in many of the current suction devices. Thus, there is a need for a device that can exclude larger items from a suction device for emptying pit latrines.
BRIEF DESCRIPTION OF DRAWINGS
• Example features and implementations are disclosed in the accompanying drawings. However, the present disclosure is not limited to the precise arrangements and instrumentalities shown.
• FIG. 1 is a side view of a self-cleaning screen device, according to one implementation.
• FIGS. 2A and 2B are side views of a self-cleaning screen device, according to other implementations.
• FIG. 3 is a side view of a self-cleaning screen device, according to another implementation.
• FIG. 4 is a side view of a suction system, according to another implementation.
• FIG. 5 is a side view of a self-cleaning screen device, according to another implementation.
• FIG. 6 is a side view of a suction system including a self-cleaning screen device, according to another implementation.
DETAILED DESCRIPTION
• Various implementations include a self-cleaning screen device. The self-cleaning screen device includes a screen and an auger. The screen is a hollow cylinder and has a screen central axis, a screen inner surface, a screen outer surface opposite and radially spaced apart from the screen inner surface, a screen first end, and a screen second end opposite and axially spaced apart from the screen first end. The screen outer surface defines a plurality of openings extending radially to the screen inner surface. The auger is helically shaped and has an auger central axis, an auger first end, and an auger second end opposite and axially spaced apart from the auger first end. The auger is disposed around at least a portion of the screen outer surface such that the auger central axis and the screen central axis are coincident with each other. The auger is rotatable about the auger central axis relative to the screen.
• Various other implementations include a suction system. The suction system includes a pump, a pipe, and a self-cleaning screen device. The pump has a suction inlet. The pipe has a pipe central axis, a pipe inner surface, a pipe outer surface opposite and radially spaced apart from the pipe inner surface, a pipe first end, and a pipe second end opposite and axially spaced apart from the pipe first end. The self-cleaning screen device includes a screen and an auger. The screen is a hollow cylinder and has a screen central axis, a screen inner surface, a screen outer surface opposite and radially spaced apart from the screen inner surface, a screen first end, and a screen second end opposite and axially spaced apart from the screen first end. The screen outer surface defines a plurality of openings extending radially to the screen inner surface. The auger is helically shaped and has an auger central axis, an auger first end, and an auger second end opposite and axially spaced apart from the auger first end. The auger is disposed around at least a portion of the screen outer surface such that the auger central axis and the screen central axis are coincident with each other. The auger is rotatable about the auger central axis relative to the screen. The screen first end is coupled to the pipe second end such that the pipe central axis and the screen central axis are coincident with each other.
• FIG. 1 shows a self-cleaning screen device100. The self-cleaning screen device100 includes ascreen102, anauger120, apipe130, ashaft140, and anauger mounting disk150. The self-cleaning screen device100 is designed to suction or otherwise cause the flow of the fluid within a pit latrine through the plurality ofopenings114 defined by the screenouter surface112 while excluding relativelylarger items199 such as garbage, rocks, plant matter, or any other item too large to fit through the plurality of openings114 (referred to as “larger items” herein). Rotation of the helicallyshaped auger120 around thescreen102 sweeps theselarger items199 away from thescreen102 to prevent the openings in thescreen102 from being clogged. Although the self-cleaning screen device100 described herein is intended to be used to remove human feces from pit latrines, the self-cleaning screen device100 can also be used to remove any fluid from a fluid body while excludinglarge items199 of any kind.
• Thescreen102 is a hollow cylindrical tube extending circumferentially around a screen central axis104. Thescreen102 has a screenfirst end106 and a screensecond end108 opposite and axially spaced apart from the screen firstend106. Thescreen102 also has a screeninner surface110 and a screenouter surface112 opposite and radially spaced apart from the screeninner surface110. The screeninner surface110 and the screenouter surface112 both extend axially from the screenfirst end106 to the screensecond end108. A portion of the screenouter surface112 defines a plurality ofopenings114 extending radially to the screeninner surface110.
• Theauger120 is helically shaped and has an auger central axis122, an augerfirst end124, and an augersecond end126 opposite and axially spaced apart from the augerfirst end124. Theauger120 extends circumferentially around the auger central axis122 as theauger120 extends axially from the augerfirst end124 to the augersecond end126. Theauger120 is disposed around the screenouter surface112 such that theauger120 extends axially along the entire portion of thescreen102 defining the plurality ofopenings114. The auger central axis122 and the screen central axis104 are coincident with each other, and theauger120 is rotatable about the auger central axis122 relative to thescreen102.
• Thepipe130 has a hollow cylindrical tube extending circumferentially around a pipe central axis132. Thepipe130 has a pipefirst end134 and a pipesecond end136 opposite and axially spaced apart from the pipefirst end134. The screenfirst end106 is coupled to the pipesecond end136 such that the pipe central axis132 and the screen central axis104 are coincident with each other.
• Theshaft140 extends along a shaft central axis142 and has a shaftfirst end144, and a shaftsecond end146 opposite and spaced apart from the shaftfirst end144. Theshaft140 is disposed inside thepipe130 and thescreen102 such that the shaft central axis142 is coincident with the pipe central axis132, the screen central axis104, and the auger central axis122.
• The shaftsecond end146 is coupled to theauger mounting disk150, and theauger mounting disk150 is coupled to the augersecond end126. Thus, the shaftsecond end146 is fixedly coupled to the augersecond end126, via theauger mounting disk150, such that theauger120 does not rotate relative to theshaft140. Theauger mounting disk150 transfers the rotational movement of theshaft140 to theauger120, causing theauger120 to rotate relative to thescreen102. Theauger120 shown inFIG. 1 is configured to rotate between300 RPM to600 RPM. This range ofauger120 rotational speeds allows theauger120 to sweep away anylarger items199 that have been suctioned to thescreen102. However, in other implementations, the rotational speed of the auger is higher than 600 RPM. Based on the suction pressure of the self-cleaning screen device100, the size and weight of thelarger items199, and the viscosity of the fluid being suctioned, a rotational speed of theauger120 can be selected such that theauger120 can sweep or deflect anylarger items199 before thelarger items199 are able to reach the screenouter surface112.
• Theauger120 shown inFIG. 1 extends helically in a clockwise direction from the augersecond end126 to the augerfirst end124 and theauger120 rotates in a counterclockwise direction as viewed axially from the augersecond end126. Because theauger120 extends helically in a clockwise direction from the augersecond end126 to the augerfirst end124, rotation of theauger120 in the counterclockwise direction as viewed from the augersecond end126 causeslarger items199 that are suctioned to thescreen102 to be swept toward the screenfirst end106 by theauger120. Because theauger120 sweeps thelarger items199 toward the screenfirst end106, which would typically be oriented as the top-most portion of thescreen102 during use, thelarger items199 are swept upwardly, rather than downwardly where thelarger items199 could accumulate and be suctioned back toward thescreen102. Also, whenlarger items199 accumulate along thescreen102 and create resistance to the rotation of theauger120, the helically clockwise direction of theauger120 and counterclockwise rotation of theauger120, as viewed from the augersecond end126, causes the axial length of theauger120 to shorten rather than elongate. This ensures that theauger120 will not be axially elongated such that theauger120 fails to resiliently return to its original axial length once the resistance is removed. However, in situations where it is desirable for theauger120 to sweep thelarger items199 suctioned to thescreen102 toward the screensecond end108, theauger120 shown inFIG. 1 can be rotated clockwise as viewed from the augersecond end126. In other implementations, the auger extends helically in a counterclockwise direction from the auger second end to the auger first end and the auger rotates in a clockwise direction as viewed axially from the auger second end. Because both the direction that the auger helically extends heliclly and the direction that the auger rotates are reversed from the implementation of theauger120 shown inFIG. 1, the auger in this implementation also sweeps thelarger items199 suctioned to the screen toward the screen first end.
• Agap128 is defined between theauger120 and the screenouter surface112 of the self-cleaningscreen device100 shown inFIG. 1. Thegap128 is 4 mm as measured in the radial direction. However, in other implementations, the gap is between 1 mm and 10 mm Including agap128 between theauger120 and screenouter surface112 prevents or lessens the chances of thelarger items199 that are suctioned to thescreen102 from becoming lodged between theauger120 and the screenouter surface112, which creates excess friction and can cause thelarger items199 to become attached to theauger120 as theauger120 rotates. As theauger120 shown inFIG. 1 rotates, theauger120 causes the surrounding fluid to flow toward the screenfirst end106. In many situations, the flow of the fluid caused by theauger120 has enough force to sweep away thelarger items199 without the need for theauger120 to contact thelarger items199.
• However, in some situations in which thelarger items299 that are suctioned to thescreen202 are not able to be swept away by the flow of fluid caused by the rotation of theauger220, theauger220 can include asweeping extension260 extending radially inwardly from theauger220 toward the auger central axis222. As shown inFIGS. 2A and 2B, thesweeping extension260 extends across thegap228 between theauger220 and the screenouter surface212. Thesweeping extension260 of the implementation of the self-cleaningscreen device200 shown inFIG. 2A includes asteel brush262 havingbristles264 that extend from theauger220 and across thegap228 to contact the screenouter surface212. Thebristles264 of thesteel brush262 are stiff enough to sweep awaylarger items299, but bendable enough to allow theauger220 to rotate without excess friction.
• FIG. 2B shows another implementation of a self-cleaningscreen device200 including asweeping extension260. Thesweeping extension260 shown inFIG. 2B is asqueegee266. Thesqueegee266 includes asoft rubber blade268 extending from theauger220 and across thegap228 to contact the screenouter surface212. Therubber blade268 is stiff enough to sweep awaylarger items299 that are suctioned to thescreen202, but bendable enough to allow theauger220 to rotate without excess friction.
• FIG. 3 shows another implementation of a self-cleaningscreen device300 similar to the self-cleaningscreen device100 shown inFIG. 1. However, inFIG. 3, theauger mounting disk350 is disposed between the screenfirst end306 and the pipe second end336. A portion of theshaft340 is coupled to theauger mounting disk350, and theauger mounting disk350 is coupled to the augerfirst end324. Theauger320 shown inFIG. 3 extends helically in a clockwise direction from the augersecond end326 to the augerfirst end324 and theauger320 rotates in a clockwise direction as viewed axially from the augersecond end326. Thus, theauger320 sweeps any larger items399 suctioned to thescreen302 toward the screensecond end308, which would be downwardly during typical use. As discussed above, this ensures that theauger320 will not be axially elongated such that theauger320 does not resiliently return to its original axial length once the resistance is removed. However, in other implementations, the auger extends helically in a counterclockwise direction from the auger second end to the auger first end and the auger rotates in a counterclockwise direction as viewed axially from the auger second end such that the auger sweeps any larger items399 suctioned to the screen toward the screen first end. In some implementations, the portion of the shaft coupled to the auger mounting disk is the shaft second end.
• In some implementations, the self-cleaning screen device includes two auger mounting disks. A first auger mounting disk is disposed at the screen first end, as shown inFIG. 3, and a second auger mounting disk is disposed at the screen second end, as shown inFIG. 1. The shaft extends to the second auger mounting disk such that the shaft second end is coupled to the second auger mounting disk and a portion of the shaft is coupled to the first auger mounting disk. As shown inFIGS. 1 and 3, the auger second end is coupled to the second auger mounting disk and the auger first end is coupled to the first auger mounting disk. Because the auger is coupled to an auger mounting disk at both of the auger first end and auger second end, the auger is prevented from axially shortening or elongating during use, as discussed above.
• FIG. 4 shows asuction system470 including a self-cleaningscreen device400 similar to the self-cleaningscreen device100 shown inFIG. 1. Thesuction system470 also includes anexcluder472, a vacuum tank, avacuum pump482, and anengine488. Theexcluder472 includes aninlet port474 for coupling the pipe first end434 to theexcluder472 and anoutlet port476 in fluid communication with theinlet port474. Thepipe430 extends between the self-cleaningscreen device400 and theexcluder472. Theexcluder472 includes amotor478 coupled to the shaft440 for rotating theauger420. Ahose480 extends from theoutlet port476 of theexcluder472 to thevacuum tank482. Thevacuum tank482 includes aremovable storage barrel484, and the fluid flowing from the self-cleaningscreen device400 to thevacuum tank482 flows into thestorage barrel484. Theengine488 drives thevacuum pump486, which creates the suction force within thesuction system470. In other implementations, the suction system includes a vacuum truck having a tank, rather than a vacuum tank, and the fluid flows directly into the tank of the vacuum truck.
• FIG. 5 shows a self-cleaningscreen device500 similar to the self-cleaningscreen device100 shown inFIG. 1, but the self-cleaningscreen device500 shown inFIG. 5 includes a second,inner auger520′. Theinner auger520′ is helically shaped and has an inner auger central axis522′, an inner augerfirst end524′, and an inner augersecond end526′ opposite and axially spaced apart from the inner augerfirst end524′. Theinner auger520′ extends circumferentially around the inner auger central axis522′ as theinner auger520′ extends axially from the inner augerfirst end524′ to the inner augersecond end526′. Theinner auger520′ is disposed inside thescreen502 adjacent the screen inner surface510 such that theinner auger520′ extends axially along the entire portion of thescreen502 defining the plurality ofopenings514. The inner auger central axis522′, the auger central axis522, and the screen central axis504 are coincident with each other, and theinner auger520′ is rotatable about the inner auger central axis522′ relative to thescreen502. Both the augersecond end526 and the inner augersecond end526′ are coupled to theauger mounting disk550 such that theauger520 and theinner auger520′ do not rotate relative to the shaft540. Theinner auger520′ can extend from the inner augersecond end526′ coupled to theauger mounting disk550 beyond the portion of thescreen502 defining the plurality ofopenings514 and into the pipe530 to aid the flow of fluid through thescreen502 and pipe530. Theinner auger520′ also serves the purpose of dislodging any solid matter or thicker fluid that becomes lodged in one of the plurality ofopenings514.
• FIG. 6 shows asuction system670 including a self-cleaning screen device600 similar to the self-cleaningscreen device500 shown inFIG. 5, but the self-cleaning screen device600 shown inFIG. 6 includes a second,inner auger620′ that extends the entire length of thepipe630. Before suction is applied to thesuction system670, theinner auger620′ is rotated to initiate the flow of the fluid from thescreen602 to thevacuum pump686. Because rotation of theinner auger620′ brings the fluid to thevacuum pump686, theinner auger620′ eliminates the need to prime thevacuum pump686 prior to use. Theinner auger620′ is helically shaped and has an inner auger central axis622′, an inner augerfirst end624′, and an inner augersecond end626′ opposite and axially spaced apart from the inner augerfirst end624′. Theinner auger620′ in this implementation also includes theshaft640, and theinner auger620′ extends circumferentially around theshaft640 as theinner auger620′ extends axially from the inner augerfirst end624′ to the inner augersecond end626′. Theinner auger620′ extends from the inner augersecond end626′ coupled to theauger mounting disk650 through thepipe630, to the inner augerfirst end624′ coupled to themotor678 of theexcluder672. Theinner auger620′ is disposed inside thescreen602 andpipe630. The inner auger central axis622′, the auger central axis622, the screen central axis604, the pipe central axis632, and the shaft central axis642 are coincident with each other, and theinner auger620′ is rotatable about the inner auger central axis622′ relative to thescreen602 andpipe630. Both the augersecond end626 and the inner augersecond end626′ are coupled to theauger mounting disk650.
• A number of example implementations are provided herein. However, it is understood that various modifications can be made without departing from the spirit and scope of the disclosure herein. As used in the specification, and in the appended claims, the singular forms “a,” “an,” “the” include plural referents unless the context clearly dictates otherwise. The term “comprising” and variations thereof as used herein is used synonymously with the term “including” and variations thereof and are open, non-limiting terms. Although the terms “comprising” and “including” have been used herein to describe various implementations, the terms “consisting essentially of” and “consisting of” can be used in place of “comprising” and “including” to provide for more specific implementations and are also disclosed.
• Disclosed are materials, systems, devices, methods, compositions, and components that can be used for, can be used in conjunction with, can be used in preparation for, or are products of the disclosed methods, systems, and devices. These and other components are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these components are disclosed that while specific reference of each various individual and collective combinations and permutations of these components may not be explicitly disclosed, each is specifically contemplated and described herein. For example, if a device is disclosed and discussed each and every combination and permutation of the device, and the modifications that are possible are specifically contemplated unless specifically indicated to the contrary. Likewise, any subset or combination of these is also specifically contemplated and disclosed. This concept applies to all aspects of this disclosure including, but not limited to, steps in methods using the disclosed systems or devices. Thus, if there are a variety of additional steps that can be performed, it is understood that each of these additional steps can be performed with any specific method steps or combination of method steps of the disclosed methods, and that each such combination or subset of combinations is specifically contemplated and should be considered disclosed.

Claims (31)

1. A self-cleaning screen device comprising:

a screen, the screen being a hollow cylinder and having a screen central axis, a screen inner surface, a screen outer surface opposite and radially spaced apart from the screen inner surface, a screen first end, and a screen second end opposite and axially spaced apart from the screen first end, wherein the screen outer surface defines a plurality of openings extending radially to the screen inner surface; and

an auger, the auger being helically shaped and having an auger central axis, an auger first end, and an auger second end opposite and axially spaced apart from the auger first end, wherein the auger is disposed around at least a portion of the screen outer surface such that the auger central axis and the screen central axis are coincident with each other, the auger being rotatable about the auger central axis relative to the screen.

2. The device ofclaim 1, further comprising a pipe having a pipe central axis, a pipe inner surface, a pipe outer surface opposite and radially spaced apart from the pipe inner surface, a pipe first end, and a pipe second end opposite and axially spaced apart from the pipe first end, wherein the screen first end is coupled to the pipe second end such that the pipe central axis and the screen central axis are coincident with each other.

3. The device ofclaim 1, further comprising a shaft having a shaft central axis, a shaft first end, and a shaft second end opposite and spaced apart from the shaft first end, wherein the shaft is fixedly coupled to the auger such that the auger does not rotate relative to the shaft.

4. The device ofclaim 3, wherein a portion of the shaft is coupled to the auger second end.

5. The device ofclaim 4, wherein the shaft second end is coupled to the auger second end.

6. The device ofclaim 4, further comprising an auger mounting disk, wherein the shaft second end is coupled to the auger mounting disk, and the auger mounting disk is coupled to the auger second end.

7. The device ofclaim 4, wherein either the auger extends helically in a clockwise direction from the auger second end to the auger first end and the auger rotates in a counterclockwise direction as viewed axially from the auger second end, or the auger extends helically in a counterclockwise direction from the auger second end to the auger first end and the auger rotates in a clockwise direction as viewed axially from the auger second end.

8. The device ofclaim 3, wherein a portion of the shaft is coupled to the auger first end.

9. The device ofclaim 8, wherein the shaft second end is coupled to the auger first end.

10. The device ofclaim 8, further comprising an auger mounting disk, wherein the portion of the shaft is coupled to the auger mounting disk, and the auger mounting disk is coupled to the auger first end.

11. The device ofclaim 8, wherein either the auger extends helically in a clockwise direction from the auger second end to the auger first end and the auger rotates in a clockwise direction as viewed axially from the auger second end, or the auger extends helically in a counterclockwise direction from the auger second end to the auger first end and the auger rotates in a counterclockwise direction as viewed axially from the auger second end.

12. The device ofclaim 1, wherein a gap is defined between the auger and the screen outer surface, the gap being 1 mm to 10 mm.

13. The device ofclaim 1, further comprising a sweeping extension extending radially inwardly from the auger toward the auger central axis.

14. The device ofclaim 13, wherein the sweeping extension comprises a steel brush.

15. The device ofclaim 13, wherein the sweeping extension comprises a squeegee.

16. The device ofclaim 1, wherein the auger rotates about the auger central axis between 300 RPM to 600 RPM.

17. A suction system comprising:

a pump having a suction inlet;

a pipe having a pipe central axis, a pipe inner surface, a pipe outer surface opposite and radially spaced apart from the pipe inner surface, a pipe first end, and a pipe second end opposite and axially spaced apart from the pipe first end;

a self-cleaning screen device comprising:

a screen, the screen being a hollow cylinder and having a screen central axis, a screen inner surface, a screen outer surface opposite and radially spaced apart from the screen inner surface, a screen first end, and a screen second end opposite and axially spaced apart from the screen first end, wherein the screen outer surface defines a plurality of openings extending radially to the screen inner surface; and

an auger, the auger being helically shaped and having an auger central axis, an auger first end, and an auger second end opposite and axially spaced apart from the auger first end, wherein the auger is disposed around at least a portion of the screen outer surface such that the auger central axis and the screen central axis are coincident with each other, the auger being rotatable about the auger central axis relative to the screen,

wherein the screen first end is coupled to the pipe second end such that the pipe central axis and the screen central axis are coincident with each other.

18. The system ofclaim 17, further comprising a shaft having a shaft central axis, a shaft first end, and a shaft second end opposite and spaced apart from the shaft first end, wherein the shaft is fixedly coupled to the auger such that the auger does not rotate relative to the shaft.

19. The system ofclaim 18, wherein a portion of the shaft is coupled to the auger second end.

20. The system ofclaim 19, wherein the shaft second end is coupled to the auger second end.

21. The system ofclaim 19, further comprising an auger mounting disk, wherein the shaft second end is coupled to the auger mounting disk, and the auger mounting disk is coupled to the auger second end.

22. The system ofclaim 19, wherein either the auger extends helically in a clockwise direction from the auger second end to the auger first end and the auger rotates in a counterclockwise direction as viewed axially from the auger second end, or the auger extends helically in a counterclockwise direction from the auger second end to the auger first end and the auger rotates in a clockwise direction as viewed axially from the auger second end.

23. The system ofclaim 17, wherein a portion of the shaft is coupled to the auger first end.

24. The system ofclaim 23, wherein the shaft second end is coupled to the auger first end.

25. The system ofclaim 23, further comprising an auger mounting disk, wherein the portion of the shaft is coupled to the auger mounting disk, and the auger mounting disk is coupled to the auger first end.

26. The system ofclaim 23, wherein either the auger extends helically in a clockwise direction from the auger second end to the auger first end and the auger rotates in a clockwise direction as viewed axially from the auger second end, or the auger extends helically in a counterclockwise direction from the auger second end to the auger first end and the auger rotates in a counterclockwise direction as viewed axially from the auger second end.

27. The system ofclaim 17, wherein a gap is defined between the auger and the screen outer surface, the gap being 1 mm to 10 mm.

28. The system ofclaim 17, further comprising a sweeping extension extending radially inwardly from the auger toward the auger central axis.

29. The system ofclaim 28, wherein the sweeping extension comprises a steel brush.

30. The system ofclaim 28, wherein the sweeping extension comprises a squeegee.

31. (canceled)

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